1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to a light emitting diode (LED) package usable for a backlight unit, such as a liquid crystal display (LCD), or a lighting apparatus, a manufacturing method thereof, and an LED array module using the same.
2. Description of the Related Art
Light emitting diodes (LEDs) have been widely used in many fields, including electronics and advertising, due to their long life and their low power consumption. Recently, there have been attempts to use LEDs as backlight units for LCD devices, and in the future, LEDs may also be widely used in common lighting systems. Therefore, there is an increasing demand for small LED packages which can efficiently dissipate heat.
LEDs used in backlight units for LCDs or in lighting apparatuses require high power consumption. However, when the temperature rises, the performance of an LED exponentially decays. Therefore, the heat dissipation properties of LEDs are important.
FIG. 1 is a sectional view of a conventional LED package. As illustrated, the LED package includes an LED 1; a heat sink member 2, on which the LED 1 is mounted; leads 3 and 3′; wires 4 and 4′, which electrically connect the LED 1 to the leads 3 and 3′; and a body 5 which covers the heat sink member 2 and the leads 3 and 3′.
The heat sink member 2 has upper and lower exposed surfaces, and an insulating layer 6 is disposed on the upper exposed surface of the heat sink member 2.
The LED 1 is bonded to the center of the insulating layer 6 by means of an adhesive 7, and first ends of the leads 3 and 3′ are positioned on the ends of the insulating layer 6. The second ends of the leads 3 and 3′ protrude from the sides of the body 5. The wires 4 and 4′ are installed to connect the LED 1 with the first ends of the leads 3 and 3′. A cap (not illustrated) may be installed on the upper portion of the body 5 for sealing the LED 1.
The above conventional LED package is mounted on a substrate 10 by soldering the pads 11 and 11′ of the substrate 10 to the second ends of the leads 3 and 3′. In addition, a solder 12 is disposed between the heat sink member 2 and the substrate 10 in the LED package. Heat generated from the LED 1 is discharged through the heat sink member 2, the solder 12, and the substrate 10.
However, this conventional LED package above has a relatively long heat transfer path (i.e. LED→insulating layer→heat sink member→solder→substrate), so that it has poor thermal radiation due to an increase in thermal resistance. Accordingly, it is not suitable for a high power LED package.
Thermal resistance Rth can be expressed as Rth=L/(k*A). According to this equation, the thermal resistance Rth decreases as a thickness (or a heat transfer path) L decreases and as thermal conductivity k and radiating area A increase. However, since such a conventional LED package has contacts made from different materials as well as a lengthened heat transfer path due to a thicknesses of the package and of the substrate, the thermal resistance thereof is increased.
When an LED package has poor thermal radiation performance, the lifetime of the LED is decreased and peripheral parts near the LED package may deteriorate or become thermally deformed because of the heat, thus possibly causing system damage.
Additionally, such a conventional LED package requires a separate wire bonding process and when such an LED is added to an LED array module, a lengthy process of soldering a plurality of packages is required, thereby increasing the number of assembly processes required and also increasing manufacturing costs.